Earlier quoted context omitted.
Removing alert is nonsense, and I don't think they will ever do (without breaking a ton of websites that use it). Why as a developer should I have to make a modal with HTML+CSS+JS to show it to just have a prompt that inform the user about something? Ok, alert is ugly, but for a lot of situations (= industrial software) it's perfectly acceptable.
Why as a user should I have to endure a website with an intrusive user of alert? I don't care what happens to websites that use alert, I never want to see my browser get locked up because of lazy devs wanting to use alerts.
Why should I as a user have to endure instagram and twitter blocking content with a delayed login prompt that cannot be canceled? Because they can. Browser APIs or not malicious developers will be malicious.